This afternoon I upgraded the Steem Monsters/Splinterlands card purchase bot at @ottermaker to accept all multi-bcx regular foil cards as well as 1 bcx Reward Edition gold cards. The pay table remains mostly the same as before, but is now per-bcx:
Send your cards to @ottermaker and it will automatically send 101% of the DEC burn value to your Steem-Engine wallet. Note that it pays out on straight bcx value for all cards including max and supermax cards, while Steem Monsters natively gives you a DEC bonus for them, so sending a maxed card will get you fewer DEC than burning it would.
It will automatically return cards if they're ineligible or if the bot doesn't have enough DEC. You can check its balance at https://steem-engine.com/?p=balances&a=ottermaker if you want to make sure. As I write this it's holding about 170,000 DEC.
I hope to open up to more gold cards as the DEC balance grows. I've chosen Rewards to start with because there are fewer different cards (20 commons and rares vs 47 in Beta) and I'm already holding quite a few of them.